In analyses using electrophoresis (for example, mass spectrometry), a cassette charged with an electrophoresis gel (separating medium) is placed in an electrophoresis chamber, and a sample that contains proteins (or DNA/RNA) is applied to the medium. After electrophoresis, the gel is removed from the cassette, and the stained gel is observed. A required portion of the gel is then cut out for analysis.
The electrophoresis gel used for the separation and development of the sample is thin and fragile. For the detection and/or quantification of the separated protein spots (bands) in the gel after the electrophoresis, it is required to (1) take out the cassette from the electrophoresis chamber, (2) disassembly the cassette and remove the gel, (3) transport the gel to a detection device (or place the gel on a flat immobilizing plate to transport it), and (4) dip the gel in a liquid (or immobilize on a support film) to prevent deformation. This is a complicated procedure, and it can be hazardous since the gel is toxic. Further, the procedure is time consuming because the gel is stained after the electrophoresis is finished. There have been proposed methods in which fluorescence-stained samples are used to omit the gel staining step and all other preceding steps (see Patent Publications 1 and 2, for example).    Patent Publication 1: Japanese Unexamined Patent Application Publication No. 215713/1993 (Tokukaihei 5-215713, published on Aug. 24, 1993).    Patent Publication 2: Japanese Unexamined Patent Application Publication No. 215714/1993 (Tokukaihei 5-215714, published on Aug. 24, 1993).    Patent Publication 3: Japanese Unexamined Patent Application Publication No. 132079/1995 (Tokukaihei 7-132079, published on May 23, 1995).    Patent Publication 4: Japanese Unexamined Patent Application Publication No. 69905/2005 (Tokukai 2005-69905, published on Mar. 17, 2005).    Patent Publication 5: Japanese Unexamined Patent Application Publication No. 77242/2005 (Tokukai 2005-77242, published on Mar. 24, 2005).    Patent Publication 6: Japanese Unexamined Patent Application Publication No. 172621/2005 (Tokukai 2005-172621, published on Jun. 30, 2005).